1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, the present invention relates to an output driver of a semiconductor device and to a method of controlling the slew rate thereof.
A claim of priority is made to Korean Patent Application No. 2003-1592 filed on Jan. 10, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
2. Description of the Related Art
In a semiconductor device, an output driver is used to output signals externally from the device. The slew rate of an output signal from the output driver is a significant factor for devices operating at a high-frequency. This is because the slew rate must generally be increased for a high-frequency operation as compared to a low-frequency operation.
The slew rate of the output signal is typically adjusted using one of two methods. In a first method, a signal output from an output driver is measured and the slew rate of the signal is adjusted using a predetermined selection signal according to the result of measurement. In a second method, the slew rate of an output signal is adjusted according to the operation of a circuit that detects a process voltage temperature (PVT) which exhibits some correlation to slew rate.
However, the first method is disadvantageous because it is generally inconvenient to measure the slew rate of the output signal using conventional measurement techniques. The second method is also disadvantageous because the slew rate is not adjusted based an actually measured slew rate, and inaccuracies may therefore be introduced.